A reservoir for use with an implantable penile prosthetic. The reservoir has a neck providing an outlet from the empty reservoir, an end on a side of the empty reservoir opposite of the neck, and a first major surface separated from a second major surface by a side wall. The first and second major surfaces are both concave and each form opposed depressions in the reservoir, wherein the side wall is connected between a first edge of the first major surface and a second edge of the second major surface, with the first major surface concave relative to the first edge and the second major surface concave relative to the second edge.
